Deadlocking self-latching locks for entryways have been available for some time for use on exterior home doors, and office doors in the United States. Locks of this type employ a spring-mounted main bolt having one curved or sloping face, and a cooperative deadlocking bolt which when depressed prevents retraction of the main bolt. In a lock of this type, a lock strike plate on the door jam permits passage of the main bolt therethrough, but depresses the deadlocking bolt. The door can thus be closed and locked from the outside without the use of a key. However, it cannot be reopened from the outside without the use of a key.
Many self-latching locks for cabinet doors and drawers have also been developed. However, pin tumbler deadlocking self-latching cabinet door and drawer locks are not generally available. U.S. Pat. No. 4,012,928 to Dauenbaugh and assigned to Keystone Consolidated Industries, Peoria, Ill., describes a self-latching, mortise-type cabinet lock for use in desk drawers and the like. The latch on this lock is not of the deadlocking type found in entryway doors. Non-deadlocking latch locks can be defeated by inserting thin material between the interfacing bolt and striker surfaces, such as a credit card to depress the latch bolt against its main spring. For these reasons, self-latching cabinet door and drawer locks have not been applied to security installations.
There are currently very large quantifies of dead bolt pin tumbler cabinet door and drawer locks installed in the United States. Locks of this type do not apply a spring bias to the bolt. Rather, the bolt is driven by rotation of a plug within a cylinder plug assembly. If the cylinder and plug assembly is of the pin tumbler variety, these locks are highly secure and as shown by the line of locks manufactured by Olympus Lock, Inc., Seattle, Wash. can be readily rekeyed. Nevertheless, a key is required to both lock and unlock cabinet doors and drawers fitted with locks of this type. It would be extremely advantageous to apply the security of a dead bolt-type cabinet door and drawer lock, with the convenience of a deadlocking self-latching entryway door lock.